Fuel

A fuel is a substance that is changed in some way to produce heat, electricity, or other forms of energy. This is usually by being burnt, although there are exceptions, such as nuclear fuel. Fuel can be divided into two main types: fossil fuels and other fuels.

Some people do not want us to use fossil fuels because they may pollute the environment. Because all fossil fuels are made out of carbon, burning them makes carbon dioxide. Some people think that too much carbon dioxide in the air may cause a greenhouse effect. Fossil fuels are also non-renewable, or renew extremely slowly (thousands of years). This means that we will eventually run out of fossil fuels.